Method of making flexible corrugated-metal walls



April 30, 1929. w. R. ZIMMERMAN METHOD OF MAKING FLEXIBLE CORRUGATED METAL WALLS Filed Oct. 6,` 1925 I NVEN TOR. WHium Rlmmerman if@ LA? vPatented Apr. 30, 1929.

UNITED STATES PATENT OFFICE.

WILLIAM n. ZIMMERMAN, or CLEVELANL, onIoQAssIGNoIz Torn-'E menor AND BAB- OOox MANUFACTURING COMPANY, or CLEVELAND, OIIIO,1A CORPORATION or OHIO.

The present invention 'relates to an' im- Y proved method of making flexible corrugated metal walls, commonly termed metal belf lows, and Vis particularly directedV to a mechanical `method of making such bellows which shall iisure greater accuracy in the wall thicknesses and particularly at the bends of tlie corrugations than is possible with the methods now in use for Imechanical- 1y forming tubes into bellows. A. further object ofithe invention is the provision of a method for more accurately tempering the Vmetal and controlling the characteristics of the metal in the' walls during the formation of the walls into corrugations, while a still `further object is the provision of an improved metal bellows having greater uniformity and sensitiveness in action than those now in use. To the accomplishment of the foregoing and related ends, said invention, then, consists of the means hereinafter fully described and particularly pointed out in the claims. I

The annexed drawing and the following description. set forth in detail one method and one product exemplifying my invention, such disclosed procedure and product constituting, however, but one of various applications of the principle ofmy invention. In said annexed drawing A Fig. V1 is a side elevation partially in section showing apparatus for performing the initial step in-my improved method of making bellows; Fig. 2 is similar view illus? trat-ing the second stepgfFi 3 is a longitudinal section showing the ormation of the corrugations after the conclusion of the second step; Fig. 4 is a view in longitudinal section illustrating the last-step in the method;` and Fig. 5 is'a longitudinal'section of the bellows at the conclusion ofthe process.

My improved method consists, briefly stated, in first forming a series of suitably spaced encircling indentations and projec' tions around a thin tube while mal'ntalnlng the length of the tube constant so that the metal is entirely stretched during this oper-v ation; then increasing the depth of the in# wardly and outwardly extending corrugations while simultaneously collapsing the tube longitudinally,

I and bending the metal in. the corrugations;

thus both stretching \M:ETIIOI or MAKING FLEXIBLE conRUeATED-METAL WALLS.

Appncanqn meaoctober s, ma serial No. sojzsaf and inallystill further collapsing the tube while Yguiding the movement of the several corrugations to prevent cooking of these durlng the completion of the forming operation. Y In Fig. 1- I have shown the first of the above steps in the formation of metallic bellows and in this Figure there is shown aV thin cylindrical tube 1 which is disposed about a shaft l,60. 2 provided with a seriesof spaced corrugating rolls 3, all of which are lixed against either relative longitudinal or rotational movement with respect to the shaft. The tube, when'so mounted upon the rolls 3, is 65 then brought into contact with a second series of rolls-4 also fixed ,upon a shaft 5 and arranged to contact the outer surface of the tube at points equidistant along its length y from the" points engaged -by the adjacent inner `rolls 3. During this inltial operation the cylindrical tube is formed with a series of outwardly projecting corrugations 6 and inwardly projecting corrugations 7, provided the outer and inner rolls are 1formed to exert 75 about equal pressure upon the tube wallwhile the depth of the inner and outer corrugations will depend upon the relative pressure exerted by the two sets of rolls, although in any event both inner and outer corrugations will 4 be" formed-,during this operation. The tube length does not shorten during this first operation. The metal in each corrugation is therefore stretched and worked more than is the case, however, if the tube length is allowed to shorten during operation, in which case the tube wall is formed into'corrugations by a combined metal stretching and bending` operation, Vin which case the bending of the metal tube wall causes 'a very slight working 90 of the metal and does not increase its temper or hardness to any appreciable degree.

After the completion of the vinitial corrugations shown in Fig. 1 the partially corrugated tube, either with or Without an anneal, de- `95 pending upon the temper which has been worked into the metal during the first o eration, which in turn depends .upon the epth to` which the corrugations arecarried at this stage, is disposed upon a second ,shaft 10 with 100 the various Loutwardly extending corrugations `engaged by. rolls 11, whichare non-rotatably mounted on the shaftrlO, but are longitudinally movable thereon. `A.second shaft 12, also carrying non-rotatable but longitudinally movable rolls 13, is then brought down upon the partially corrugated tube, the rolls 13 engaging in the crests of the inwardly ex'- tending corrugations. As the two shafts are made to approach each other both the inner and outer corrugations are deepened and are narrowed by the same action, since as the rolls are all floating on their shafts the tube length will shorten during this operation and theI corrugations will be brought closer to each other, producing corrugations of the form shown in Fig. 3. Springs 18 are interposed between the various rolls 13 on the shaft 12 and the rolls 11 on the shaft 10 to provide proper initial spacing of these rolls and to also, to some extent stabilize the collapsing action of the rolls during the progress of the second operation illustrated in' PThe vary thickness of the metal of the tube after the completion of the second -operation is shown in Fig. 3, and it will be understood that the effect `ol the second operation will be to materially decrease the hardness and tem-I per of the crests'of both inner and outer corrugations, the temperature varying from a maximum at the crests of` the c'orrugations to a minimum at the center of the intermediate flat connecting portions 14E. v

The final step in the forming of the bellows consists in collapsingformodifying the shape of the various corrugations by compressing the tube endwise. This step, which may be accomplished in various ways; is illustrated in Fig. 4 as'being carried yout by mounting the tube about a tubular member 15 having a diameter very slightly less than the desired final inside diameter of the bellows, after which the tubular plunger 16 is moved longitudinally of the element 15 against'one end of the bellows, while the other end of the bellows is mount-ed uponl a base 17 The elfect of this collapsing operation is to greatly narrow and to slightly deepen'the various corrugations, and to slightly increase the outside diameter of the bellows and to decrease the inside diameter. The action on each corrugation is almost purely a bending action, there being. however, a suflicient stretching y of the metal at the bends to effect the increase in the diameter which is referred to and to bring the inner corrugations into substantial contact with the tubular guide 15. The function of the guide 15 is to determine and limit the inside diameter and to act also as a guide for the corrugations in. the deformation, which is here carried out, in this way preventing the cooking of the corrugations, which sometimes .results if -the collapsing operation is performed without any suchguiding means.

Other forms may be employed embodying the features of my invention instead o the one here explained, change being made inthe preventing the shortening of the tube, deepening and narrowing the inwardly formed corrugations while permitting the tube length to shorten, and then collapsing the corrugated tube longitudinally to bring the corrugations into substantial parallelism while preventing the corrugations from displacement out of planes at right angles to the axis of the tube. l

2. ln a method `of making corrugated metallic bellows from cylindrical tubes, the steps which consist in mechanically forming spaced alternated inwardly and outwardly extending encircling corrugations in a cylindrical tube by stretching the metal of the tube wall into such corrugations, narrowing and deepening such inwardly formed corrugations by a combined bending and stretching action, and then converting such corrugations into corrugations having substantial parallel walls by a mechanical collapsing operation while preventing dis/placement of the various corrugations from planesy at right angles to i the axis of the tube..

3. ln a method of making corrugated metallic bellows from cylindrical tubes, the steps which consist in lmechanically forming spaced alternated inwardly and outwardly extending encircling corrugations in a cylindrical tube by stretching the metal of the tube wall into such corrugations while preventing the shortening of the tube between the outermost 'corrugationa narrowing and deepening such inwardly formed corrugations by a combined bending and stretching action, and thenV shortening the entire tube length a material amount by a change in the conformation of the various corrugations effected solely by an endwise pressure on the tube.

l. In a method of making corrugated metallic bellows from cylindrical tubes, the steps which consist in forming spaced alternated inwardly and outwardly extending encircling corrugations in a tubular wall while preventing the shortening of the tube between the outermost corrugations, deepening and narrowing such formed corrugations while permitting the tube length to shorten A. and then collapsing the corrugated tube longitudinally to bring the corrugations into substantial parallelism. y 5. In a method of making corrugated f gated tube longitudinally to bring the corrumetallic bellows from cylindrical tubes, the steps which consist in forming spaced alter- :cated inwardly and outwardly extending,lr encircling corrugations in a tubular Wall, deepening and narrowing the inwardlyT formed eorrugations and then collapsing the corrument out of planes at right angles to the axis 1o of the tube.

Signed by me this 11th day of Sept., 1925.

WILLIAM ZIMMERMAN. 

